Decontamination systems typically use gaseous chemical sterilants, e.g., ozone, or vaporous chemical sterilants, such as, vaporized hydrogen peroxide (“VHP”), to deactivate biocontamination and/or neutralize chemical contamination in a region, such as hotel rooms and motor vehicles, and on internal and external surfaces of food and beverage containers (e.g., bottles). Such chemical sterilants are also typically used to deactivate biocontamination harbored on internal or external surfaces of medical instruments and other items used in the health care industry.
A decontamination cycle of decontamination systems for decontaminating a region (such as a room) typically includes an exposure phase wherein the chemical sterilant is introduced into the region and maintained at a predetermined concentration for a predetermined period of time. Following the exposure phase, the decontamination system performs an aeration phase wherein the concentration of the chemical sterilant is reduced. A destroyer in the decontamination system is typically used to reduce the concentration of the chemical sterilant. The destroyer includes a material that is chemically active (e.g., destructive or reactive) with respect to molecules of the chemical sterilant as, by way of example and not limitation, by catalysis, physical forces, electrical forces or chemical reaction. The aeration phase continues until the concentration of the chemical sterilant within the region is reduced to below a predetermined threshold level.
When decontaminating a room, such as a hotel room, with VHP, the concentration of VHP within the room needs to be reduced to below 1 part per million (1 ppm), especially, if humans are to enter the room without protective equipment. It is therefore desirable that the concentration of the chemical sterilant in the room be reduced to below the threshold value of 1 ppm as quickly as possible. With existing systems, it is difficult to reduce the concentration of VHP within the room to below the 1 ppm threshold level in a reasonable amount of time.
One factor that influences the ability of present decontamination systems to quickly reduce the concentration of VHP in the room is the efficiency of the destroyer in the decontamination system. Presently available destroyers for VHP are constructed with materials that are catalytic to the destruction of VHP, i.e., a catalyst. The VHP molecules are catalytically destroyed upon contact with the surface of the catalytic material. However, during operation of existing decontamination systems, some of the VHP molecules simply pass through the destroyer without making contact with the catalytic material. This is especially true at low concentrations of VHP. In a closed-loop system, these VHP molecules are then re-injected into the region only to be evacuated from the region and passed through the destroyer again. In some situations, the VHP molecule may pass through the destroyer several times before the VHP molecule contacts the catalytic material in the destroyer. Therefore, it would be advantageous to have a method and apparatus that minimizes the number of VHP molecules that are re-injected into the air in the room.
It is also believed that part of the difficulty in quickly reducing the concentration of the VHP in the room is tied to the sorption of VHP molecules by the surface of the walls that define the room and the surface of other articles in the room. The VHP molecules that are disposed on or in the surfaces must first diffuse into the air before they can be circulated through the destroyer. Typically, these VHP molecules diffuse into the air as a result of thermal effects or because of a concentration gradient that exists between the surfaces and the air. It would be advantageous to have a method and apparatus that exerts a force on the VHP molecules on or in the surfaces to accelerate their diffusion into the air.
Similar problems arise when VHP is used to decontaminate containers used in the food and beverage industry (e.g., bottles and food containers). It is believed that VHP is adsorbed to the surfaces of the containers. Desorption and adsorption of VHP molecules from a surface is a dynamic process. Without an external force to pull the VHP molecules from the surface of the container, some of the VHP molecules will desorb from the surface while others will adsorb back onto the surface of the container. It would thus be advantageous to force the desorption of VHP molecules from the surface of the container and destroy the VHP molecules before they adsorb back onto the surface of the container.
The present invention overcomes these and other problems and provides a method and apparatus for removing chemical sterilant from a medium by forcing the motion of a chemical sterilant molecule that has an induced or permanent electrical dipole moment.